From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754978Ab0EaKGb (ORCPT ); Mon, 31 May 2010 06:06:31 -0400 Received: from hera.kernel.org ([140.211.167.34]:47243 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751823Ab0EaKG3 (ORCPT ); Mon, 31 May 2010 06:06:29 -0400 Message-ID: <4C038A08.8090209@kernel.org> Date: Mon, 31 May 2010 12:06:00 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 MIME-Version: 1.0 To: Peter Zijlstra CC: mingo@elte.hu, linux-kernel@vger.kernel.org, Rusty Russell , Mike Galbraith Subject: Re: [PATCH 2/4] sched: implement __set_cpus_allowed() References: <1273747705-7829-1-git-send-email-tj@kernel.org> <1273747705-7829-3-git-send-email-tj@kernel.org> <1275292866.27810.21441.camel@twins> <4C03879A.8030505@kernel.org> <1275300084.27810.21850.camel@twins> <1275300165.27810.21858.camel@twins> In-Reply-To: <1275300165.27810.21858.camel@twins> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Mon, 31 May 2010 10:06:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/31/2010 12:02 PM, Peter Zijlstra wrote: > On Mon, 2010-05-31 at 12:01 +0200, Peter Zijlstra wrote: >>> but we can update cpu_active mask before other >>> CPU_UP_PREPARE notifiers are executed so that it's symmetrical to cpu >>> down path and then this problem goes away the exact same way, right? >> >> Ah, no, we cannot mark it active before its actually up, because at that >> time we'll actually try and run stuff on it, which clearly won't work >> when its not there to run stuff. > > So we should clear it _before_ we go down, and set it _after_ we're up. > Yeah, sure, I misspoke. I meant CPU_ONLINE not CPU_UP_PREPARE. So, we can mark a cpu active before other CPU_ONLINE callbacks are run. Thanks. -- tejun